BASRA, Iraq, Feb 12 (Reuters) - Masked gunmen assassinated a senior judge in the southern Iraqi city of Basra on Saturday, a Reuters witness and doctors said. Video footage showed the body of the judge, Taha al-Amiri, lying in a hospital mortuary following the attack. Witnesses said his vehicle was stopped by four masked gunmen as he drove through the centre of Basra, Iraq's second largest city, in the far south of the country. Two of the gunmen got out and opened fire, killing the judge instantly. His driver was wounded in the attack. It is the second assassination...